The 3 toilets in my rental house is taking turns to make self flushing.?

Question

It just happens once in a while, from a few minutes to half an hour or so. We just had a plumber in to change the valve and flapper a few weeks ago. It was good then. I wonder if it is because of the old pipe since the house is old and the plumber said the pipe is rusting inside. Please help! Thank you.

Answer 1

if all toilets are flushing themselves it means water is filling the bowl to the point where the gravity flush forces the toilet flush  ,water is getting into the bowl  by one of four ways  .

1. The flappers aren't seating properly . did the plumber use the correct flapper for the toilet ? is the seat of the flapper have some growth on it and not letting the surface of the flapper seat properly , you can remedey this buy roughing up the surface with some sand paper or emery cloth .                                                                                                                                                                                                         2  the tank overflow  gasket is not sealing anylonger , this is the gasket at the bottom  of the tank on the inside, to see if it the problem  , turn the water off to the toilet and let the water drain out by itself if it drops lower than the flapper seat   and drains until all but dry than that gasket is leaking .                                                                                                                                                                                                     3 If the fill valves were replaced  and they plumber installed  a new fluidmaster fill valve and the  fill tube  ( the little black tube that goes in the overflow tube ) was not cut to the proper length  it will cause the fill valve to not shut off  , if you see that refill tube shoved way down on the  overflow tube that could be  the answer,                                                                                             4 does the water run over top of the overflow ? if so  than the fill valve may have some sediment under the seat and not closing properly .maybe from rusty pipes like your plumber said                                                                                                             Have you called the plumber back  ? he should come out and correct what he should have corrected  the first time . two  weeks is not a very good warranty of work performed .

Answer 2

The flappers are still leaking.  When the water level drops to a certain point, the flush valve turns on to replenish the water.  The new flappers were either defective or improperly installed.  Another cause could be the seat that the flapper sits on.  It might need to be cleaned.  It's highly unlikely all three could be defective.